Semiconductor memory is an important part of modern electronics. Semiconductor memory may be divided into major categories. Two of these categories include volatile memory, which loses its content when power to the device is switched off, and nonvolatile memory, which retains its content when power to the device is switched off. Like other silicon technology, nonvolatile memory has been growing in density and performance. This growth in density and performance has generally followed Moore's law.
A further subcategory of nonvolatile memory is called flash memory. Flash memory can typically be electrically erased and reprogrammed without being removed and placed in a special programming device. The growth of battery powered electronics such as mobile phones, digital cameras, personal digital assistants (PDAs), and MP3 players has fueled demand for flash memory. Flash memory may be used to store such information as firmware, identification and security codes, trimming of analog functions, system parameters, and user programmable options. Thus, flash memory devices are now included in virtually all modern electronic devices.